As production processes of glycidyl ethers, there have heretofore been mainly known a single-stage process in which an alcohol and an .alpha.-epihalohydrin are reacted with each other by an alkali in the presence of a phase-transfer catalyst such as a quaternary ammonium salt, and a two-stage process in which an alcohol and an .alpha.-epihalohydrin are reacted with each other in the presence of an acid catalyst to form a halohydrin ether, and the halohydrin ether is then cyclized by an alkali. However, in the single-stage process, it is necessary to use the .alpha.-epihalohydrin in excess in order to avoid further addition of the alcohol to the formed glycidyl ether. In the two-stage process, the conversion of the alcohol becomes low when the acid catalyst is a Br.O slashed.nsted acid such as sulfuric acid, while a further addition reaction of the .alpha.-epihalohydrin to the formed halohydrin ether tends to occur when a high-active Lewis acid catalyst such as boron trifluoride or tin tetrachloride is used. In order to avoid this reaction, it is necessary to use the alcohol in excess to the .alpha.-epihalohydrin. Besides, the use of a metal chloride such as aluminum chloride, tin chloride or iron chloride as the Lewis acid catalyst also involves problems that the catalyst is deactivated by alcoholysis, and that free chlorine generated reacts with the .alpha.-epihalohydrin. Further, in order to efficiently conduct the ring closure of the halohydrin ether by the alkali, there is also a problem that a hydrophilic solvent and a phase-transfer catalyst must be used.
Processes for producing a dialkyl glyceryl ether include a process in which an alcohol is reacted with an .alpha.-epihalohydrin in the presence of an alkali, and a process in which glycerol is reacted with an alkyl halide in the presence of an alkali. However, both processes require to use the alcohol or alkyl halide in great excess and involve a problem that it is extremely difficult to introduce 2 different alkyl groups at the same time. When an alcohol is reacted with glycidyl ether in the presence of an alkali or acid catalyst, a dialkyl glycidyl ether can be obtained with the alkyl groups freely selected. However, in the case where the alkali is used, it is necessary to use the alcohol in excess in order to avoid an additional reaction of the formed product. There is also a problem that glycidyl ether is partially hydrolyzed. In the case where the acid is used on the other hand, there is a problem that glycidyl ether undergoes polymerization.
Production processes of an alkyl glycoside include a process in which a sugar is reacted directly with a higher alcohol in the presence of an acid catalyst (U.S. Pat. No. 3,839,318 etc.). However, this process involves a problem that when the sugar is caused to coexist with water and the acid catalyst, the sugar undergoes condensation to form a by-product, so that the yield is lowered, and the deterioration of hue is incurred. When the sugar is a monosaccharide in particular, the alkyl glycoside formed may condense with the monosaccharide in some cases, so that the yield of the alkyl glycoside is markedly lowered. As a process for preventing such condensation of the sugar itself, or of the alkyl glycoside formed with the sugar to obtain the intended alkyl glycoside at a high yield, a process in which a higher alcohol is used in excess to the sugar has been known (Japanese Patent Application Laid-Open No. 5199/1984 etc.). However, this process requires to remove excessive unreacted alcohol. In the course of this operation, deterioration of smell and the like may occur in some cases, and there is an economical problem that the productivity is markedly lowered. There is also a problem that the degree of condensation of the sugar is rapidly raised as the conversion of the sugar becomes high, and the concentration of the alkyl glycoside in the system is raised.
Accordingly, it is an object of the present invention to provide an acid catalyst which is suitable for use in a variety of acid-catalyzed reactions of alcohols, i.e., reactions with carbonyl compounds, such as esterification, transesterification, acetalization and ketalization, etherification, ring-opening reactions of epoxy compounds, etc. in addition to the above-described respective reactions, is not deactivated by alcoholysis, has a sufficient activity, can easily control a reaction catalyzed thereby and scarcely causes side reactions.
Another object of the present invention is to provide a production process of an ester, acetal, ketal, ether or alkyl glycoside making use of the above catalyst, by which the intended product can be produced at a high yield even when starting materials are used in an almost equimolar proportion.